“Ordinary” hydrogen (H) has a nucleus consisting of one proton and it has an atomic weight of 1. However, there is also an isotope of hydrogen that has a nucleus consisting of one proton and one neutron. This isotope is called deuterium, and chemical reference materials commonly use either the symbol “D” or the symbol “2H” to represent deuterium. Deuterium has an atomic weight of 2, and it is often referred to as heavy hydrogen.
Deuterium occurs in nature, but only in very small quantities compared with ordinary hydrogen. Nonetheless, because of deuterium's presence in nature, and because it is an isotope of ordinary hydrogen, the atomic weight of hydrogen is typically listed in reference charts and tables as slightly greater than one, which reflects the weighted average of ordinary hydrogen and deuterium as they occur in nature. Various processes are known in the art for separating the isotopes of hydrogen such that concentrations of deuterium may be produced.
Water molecules may be formed either with ordinary hydrogen or with deuterium. The term “ordinary water” is generally used to refer to a compound of oxygen and ordinary hydrogen, or a compound made from oxygen and hydrogen composed of oxygen with ordinary hydrogen mixed with a naturally-occurring amount of deuterium. When deuterium in a form that is concentrated above naturally-occurring proportions is compounded with hydrogen, the resulting compound is referred to as “hydrogen deuteride” or (more commonly) referred to as “heavy water.” Ordinary water is typically denoted by the chemical symbol “H2O,” whereas heavy water is typically denoted either by the chemical symbol “D2O” or “2H2O.”
Heavy water is used as a neutron moderator and a coolant for nuclear power reactors that use natural uranium as a fuel. Heavy water is also a convenient storage media for deuterium, which is used as a fuel in nuclear fusion reactors, as a wave length shifting material in laser applications, and in various scientific research applications. Heavy water is typically made by isotopically enriching the percentage of hydrogen deuteride in ordinary water using various chemical or thermal enrichment processes. These are generally quite expensive and slow processes. What is needed therefore are improved methods of manufacturing heavy water.